Bristleworms Under Clam

[FSOL]

Hey everyone,

Recently I kept noticing my clams won't stay up open, and I was putting the blame on my longnose butterfly.
The thought crossed my mind to lift the clams out and look under it. I saw 1 or 2 small (quarter inch to half inch) sized bristleworms under the clams. I did manage to get rid of them, but could they be the responsible ones to keep my clams from opening up all day?
Also, do they stay outside and underneath the clam or can they go inside of it and kill it?

I'm paranoid, cuz I have three nice looking clams. I went and purchased an arrow crab and I hope it'll rid the tank of bristleworms. What else can I do here to help?
I'm also thinking of getting rid of the longnose, cuz sometimes it nips at the clams.

Thanks

[derekman]

they can and will irritate the clams, but will not attack the clam unless it is already dying. I have BB now but when I had a DSB I had to put my T.Derasa on the rocks, it was happiest there

[Sk8r]

My crocea has no problem with hundreds of them in the tank, and I'm sure a few in his vicinity. He grows a row of scutes every other month and stays fully extended as long as the light is on. I'd look more closely at the butterfly. [I've tried putting him in the rockwork, but he prefers the sand, and always goes to the same spot.]

[FSOL]

Thanks guys. I don't like them on the rocks. I've thought about putting a flat small piece of rock on the sandbed and placing the clam on it, but I think the worms can still attack it that way.
All 3 of these clams were doing great until the day I brought the butterfly in, and unfortunately I also saw the worms under them that same day, so it's hard to say who's the bastard causing this.
What I don't understand is if it's the butterfly and they close up when it nips at them, how come they don't just open back up again once the butterfly is gone.